1. Field of the Invention
The present invention relates to a refrigerant compressor such as a swash plate type refrigerant compressor adapted for being used in an airconditioning or a climate control system of automobiles, and more particularly, it relates to a multi-piston type refrigerant compressor provided with a muffling unit in which damping of both suction and discharge gas pulsations is achieved.
2. Description of the Related Art
U.S. Pat. No. 4,534,710 discloses a multi-piston swash plate type compressor provided with a muffling unit having therein suction and discharge damping chambers. The muffling unit of the multi-piston type compressor of U.S. Pat. No. 4,534,710 is formed by outer walls extending upwards from the outer circumference of the cylinder block of the compressor. In the muffling unit, the suction and discharge pulsation damping chambers are separately defined to respectively deaden suction gas pulsation and discharge gas pulsation. The uppermost opening of the muffling unit is sealingly covered by a flat covering plate which extends horizontally when the compressor is mounted in an engine compartment of an automobile. Nevertheless, a suction pipe for introducing a refrigerant gas before compression from an airconditioning system into the compressor and a discharge pipe for discharging the compressed refrigerant gas toward the airconditioning system are connected to suction and discharge ports formed in the two mutually rectangular upright walls of the muffling unit, and therefore, when the compressor is mounted in an engine compartment of an automobile, an operator finds difficulty in arranging refrigerant-gas pipes and hoses in the narrow space available within the engine compartment.
Another conventional multi-piston type compressor is provided with a muffling unit integral with the cylinder block of the compressor, shown in FIGS. 5 and 6, in which an arrangement and an outer shape of the muffling unit is similar to that of the compressor of U.S. Pat. No. 4,534,710. However, the suction and discharge pipes for introducing the refrigerant gas before compression and discharging the compressed refrigerant gas are connected to suction and discharge ports formed in the flat covering plate of the muffling unit so that;the suction and discharge pipes extend in parallel with one another.
Thus, when the compressor is mounted in an engine compartment of an automobile, the posture of the compressor is in that the covering plate of the muffling unit generally extends horizontally. In order to connect the suction and discharge pipes to the suction and discharge ports of the covering plate, these pipes must have a right-angle pipe end having one end connected to the suction or discharge port of the covering plate and the other end from which a lateral portion of the suction or discharge pipe horizontally extends. Thus, the latter conventional multi-piston type refrigerant compressor creates various problems as set forth below.
(1) An additional space is required in the engine compartment to connect the respective right-angle pipe ends of the suction and discharge pipes to the suction and discharge ports of the covering plate of the integral muffling unit of the compressor.
(2) The suction and discharge damping chambers separated from one another by a partition wall within the muffling unit have an identical vertical depth, and therefore, the partition wall has a large surface area through which the heat of the compressed refrigerant gas in the discharge damping chamber is transmitted to the refrigerant gas before compression (the suction gas) in the suction damping chamber. Accordingly, the suction gas is warmed before it enters the suction chamber or chambers of the compressor, and the density of the suction gas is reduced. Therefore, when the warmed suction gas is continuously compressed, the compression efficiency of the compressor is necessarily lowered.
(3) The outer upright walls and the separation wall of the muffling unit are very high, and therefore, the weight of the compressor provided with the integral muffling unit is large.